Indicating mechanism



May 14,1946 L. s. wlLLlAMs NDICATING MECHANISM Filed Oct. 24, 1942 4 Sheets-Sheet l Y 4ul'jl/I/Els/TOR. 0W/'ence '5. h////ams BY d), i @MRW May 14, 1946.

ll.. s. WILLIAMS 2,400,277

INDICATING MECHANISM Filed Oct. 24, 1942 4 Sheets-Sheet 2 INVEIyTpR. 0W/ence 5. PVM/mms May 14, 1946- L. s. WILLIAMS 2,400,277 INDICATING MEGHANISM Filed oct. 24, 1942 4 sheets-sheet 3 IN1/wrok. Law/'ence 5. H////ams TToRNEYs.

Y May 14,1946. L. s. WILLIAMS INDICATING MEGHANISM Filed 00h24, 1942 4 sheets-sheet 4 INVENTOR. Lawrence 5. M/f//fdms Patented May 14," 1946 UNITED STATES PATENT OFFICE` INDICATING MECHANISM Lawrence S. Williams, Toledo, Ohio, assignor to Toledo Scale Company, Toledo, Ohio, a corporation of New Jersey Application October 24, 1942, Serial No. 463,265

' (Cl. 177--311l 2 claims.

This invention relates to indicating mechanisms for use with instruments which must be brought to or maintained at a correct positionand which have a range of positions both above and below, or on each side of the correct position, in which the operation employing the instrument also requires the concentrated attention of the operator to the operation so that it is impossible for him to view or watch a visual indicator.

In many delicate operations in industry, such as for example, the weighing of minute quantities of liquids or compounds, there is required the full attention oi the operator to the operation itself. In general such operations have been carried out on delicate weighing scales where close attention is required to the indicator in order to reach an accurate result. This requirement of close attention has generally been a function of the operators eyesight, and thus the amount of close attention which the operator could give had to be divided between watching the indicator and the operation itself.

Similarly many other operations, such as gun sighting. close tolerance machine tool operation and the operation of electrical equipment at closely specified points, require the undivided attention of the operator to other variables in the operation than the instruments themselves. Working under these conditions is rendered even more dinicult when, as is often the case, the operators position in order to carry out the operation does not permit him to view the instrument. or the light available is inadequate to permit him to read the instrument.

Delicate operations of the nature above specined, due to the necessity of the use oi the eye in reading the instrument indicators, has prevented any oi such work being done by slghtless operators. It has, therefore, been impossible to employ blind people in any of the many simple weighing, controlling or operating positions in which, due to the use oi controlling instruments, eyesight has been essential. Y Y

It is an object of this invention to provide an indicating mechanism for a measuring or indicating instrument which will enable accurate and fast operations employing such instrument by sightless operators and by sighted operators under conditions such as total darkness which preclude visible indication.

It is a further object of this invention to provide an indicating mechanism which will permit operators engaging in delicate operationsrequb ing their full and undistracted attention, and in particular the attention of their eyes, to devote their entire attention, and will indicate approach to and arrival at a desired exact position of the instrument with which it is employed by means of the sense of hearing.

It is a further object of this invention to provide a delicate weighing scale for the weighing of specified quantities of materials in which the operation of weighing itself requires the full visual attention of the operator which will indicate the approach to and arrival at the desired weight by means of an audible indication rather than a visual indication.

It is a still further object of this invention to provide a weighing scale enabling accurate and fast weighments by blind operators.

More specific objects and advantages are apparent from the description, in which reference is had to the accompanying drawings illustrating a preferred form oi' scale embodying the invention.

In the drawings: y

Fig. I is a view, in elevation, of a weighing scale adapted to be employed with indicating mechanism embodying the invention, certain parts being shown in dotted lines.

Fig. 1I is a view, in elevation, oi' a control box and instrument panel adapted to be employed with the scale embodying the invention.

Fig. III is a fragmentary view oi' the indicating 30 mechanism of the weighing scale shown in Fig. I.

Fig, IV is a vertical sectional view, taken substantially on the line IV`IV of Fig. III.

Fig. V is a fragmentary view of signal generating means.

Fig. VI is a view taken from the left side of Fig. V but on a smaller scale.

Fig. VII is a detailed view showing signal creating mechanism, taken substantially on the line VII--VII of Fig. V.

Fig. VIlI is a detailed view, in elevation, of the mechanism shown in Fig. VII but taken from the position shown by the line VIII--VIII in Fig. V.

Fig. IX is an illustration of the interlocking nature of the signals generated by the mechanism shown in Fig. V.

Fig. X is a fragmentary plan view, taken substantially on the line X-X of Fig. V.

Fig. XI is a schematic wiring diagram of electrical apparatus employed with an indicating mechanism embodying the invention.

'I'hese specific drawings and the specific description that follows merely disclose and illustrate the invention and are not intended to impose limitations upon the claims.

A weighing scale adapted to be employed with indicating mechanism embodying the invention comprises a base is in which is pivotally mounted an even-armed lever il on each end of which there is supported a platter spider i2. On the upper surface of each of the spiders I2 there is located a load-receiving platter il, and extending downwardly from each of the spiders I2 is a boss Il, which bosses are connected by a check link Il. A bracket Il, secured to one of the spiders l2, extends beneath the end of an indication tower I1 erected on the base In at one end thereof. To the innermost end of the bracket I6 there is secured an angle plate Il, to the upper end of which is attached a yoke I9. A pair of spiral springs 2l are each connected at their outermost ends to the yoke It and at their innermost ends to a triangularly-shaped arm 2i of an indicator 22 secured to a hub 2l which is mounted on an indicator shaft 24 journaled in bali bearings 2l. The bearings 2t are heid in a pair of bearing retainers 2i which are secured on a mounting post 21 mounted within and extending upwardly inside of the indication tower I1. At the uppermost end of the post 21 there is mounted a short arcuate chart 28 on which is scribed a series of under and over" indicia 2l and a zero indicium il. 'I'he arcuate lower edge of the chart 28 is closely adjacent the line of movement of a pointer ll of the indicator 22 with which the indicia 29 cooperates for visually indicating the condition of balance existing between the material on the two platters II. (On one of which a weight usually is placed, the substance to be weighed being placed on the other.) The chart 2l and pointer Il are visible through a windowed opening I2 in the front wall of the indication tower I1.

An arm It, which is mountedat its lower end on the front one of the bearing retainers 2G, is angularly movable through a slight angle by means of a link Il which is riveted to the arm Il and has a threaded end extending through a positioning plate il on each side of which there is located an adjusting nut It. On the upper end of the arm Il there is secured a bracket I1, of non-conducting material. on which are mounted two condenser plates Il and le. The condenser plates Il and Il are formed substantially in the shape of sections of the wail of a hollow cylinder and have a radius of curvature slightly smaller than the radius of curvature described by the movement of a smaller condenser plate lil which is mounted on the indicator 22 and which moves along above the condenser plates 3l and 20.

Because of the slight difference in radii. as the indicator 22 moves away from its balance position (its centrally located position as shown in Fig. III). the air gap between the condenser plate 40 and that one of the plates Il or II, over which the plate Il is moving, increases, thus decreasing the capacity of the condenser.

Audible indications of approach to, and arrival at. a condition of balance, are appreciable in a pair of earphones 4I (Fig. XI) which are connectable into a pair of earphone jacks 42 located on the' exterior of the instrument panel u, as shown in Fig. II. The audible indication of the operation of the scale consists of a series of dots and dashes which are generated in the electrical mechanism the device and audible in the earphones ll. These dots and dashes are graphically shown in Fig. IX and comprise a dot-dash combination forming theietter A of the Morse code when the scale is below or under the balance condition. and a dash-dot. or the letter .N of the Morse code. when the scale is above or over balance condition. The tone of which these sisnals are formed is created in a hummer 4l of standard commercial type, which comprises a transformer 45 and carbon button microphone u energized by a source of direct current 41 when a main switch Il of the device is closed. One lead from the secondary coil of the transformer 4l has a common connection to ground and to one side of a condenser 4l, which is shunted between the output leads of the transformer ll, and also to a lead 50. The lead 50 is connected to a Jack 5I into which a lead 52 from the main scale housing is connectable. The lead B2 is connected to the ground and to the indicator 22 and thus to the condenser plate 40 mounted on the indicator 22. The other side of the output of the secondary coil of the transformer la is connected to one side of the primary of an earphone coupling transformer i3 which is in series with a choke coil Il, the other side of which is connected to a wire feeler 55. The feeler 55 is engageable with either of a pair of contacts 56 and 51 which are connected through leads Il and I9, jacks Il and 6i and leads 82 and 6l in the main scale housing, to the two condenser plates Il and Il. respectively. A small resistance N is shunted around each of the contacts $6 and B1. 'I'he secondary coil of the earphone coupling transformer 52 has a grounded resistance 65 shunted between those leads which are connected to the two phone jacks 42.

The hummer" current, which is created by the hummer M, thus flows through the primary of the transformer ll, the choke coil Il and the feeler 55 whence it is divided between the contacts 56 and 51. and consequently the condenser plates 3! and 3l, respectively, by means of a cam BB (Figs. VII and VIII) which moves the feeler alternately into contact with the contacts Il and l1, being rotated at constant speed by a geared motor 61. The motor 81 is wired in parallelism with an on and off lamp Il to the main switch u and an outside power source Il. The motor B1, its gearing, the frame for the cam 06. and the feeler and contacts il, Il and I1, are located within a soundproof housing 10 to prevent the clicking sound of the feeler Il. engaging with the contacts 58 and Il, from disturbing the operator.

The cam O6 rotates in the direction of the arrows in Figs. VII, VIII and IU, and has two raised surfaces 1I and 12 which are engaged with the feeler il! in that order. 'I'he raised surface 1i corresponds' to a dash in the Morse code and is engaged with the feeler-*ll to force the feeler against the contact 58 for a length of time corresponding to the duration of a dash in the Morse system. 'I'he raised surface 12 similarly causes a signal lasting throughout the length of time occupied by a dot in the Morse system. The raised surfaces 1i and 12 are separated by two depressed surfaces 'Il and 14 which by passing beneath the feeler l! in that order permit it to drop and make the contact 81. lThe low surface 1I has a circumferential length substantially equal to that of the raised surface 1l, and the low surface 14 is substantially equal in length to the raised surface 12. The two surfaces 1I and 1I thus permit the feeler li toengage the contact B1 for periods of time corresponding to a dash and a dot, in that order. in the Morse system. As can be seen by comparing Figs. VIII and IX (reading from the left in Fig. IX and starting the cam Il from the position shown in F18. VIH), the relationship is thus: When the surface 1I contacts the feeler Il it causes the iirst dash at the left of Fig. IX. The

surface 14 breaks contact between the feel'er 55 i and contact 56 and establishes contact between" the feeler 55 and the contact 51, forming the rst dot in the upper row of Fig. IX and the space between the dash and rst dot in the lower row of Fig. IX. Similarly, the raised contact 12 forms the space between the iirst dot and first dash in the upper line andfcrms the first dot in the lower line. Continued rotation of the cam 66 at constant speed thus creates intermeshed "N" and A signals which are each sent over one of the two branches of the circuit connected to the condenser plates 39 and 38 respectively.

Thus there are proceeding through the branch of the circuit leading to the condenser plate 38 a series of N signals. When the indicator 22 is at the left, and thus the scale is below its balance position, the condenser formed by the common plate 40 and the condenser plate 38 is in position to permit the A signal to flow across between the plates to th ground and the lead 52, through the jack 5| and thelead 50 back'to the hummer transformer 45, this circuit being coupled by the transformer 53 the signal is audible in the earphones 4I. As the scale approaches zero and the indicator 22 swings to the right, due to the differences in the radii of the condenser plate 38 and the condenser plate 40, the capacity of the condenser formed thereby increases and thus the volume of the A signal increases as the scale approaches zero. When a condition of balance is realized, and the common `plate 40 is located equipped With the herein disclosed audio indicating means. These instruments, for example, may be navigation compasses, gun-sighting apparatus, machintii"tool indicators, tachometers, electrical meters, and pressure gauges and meters of varied forms and purposes.

The embodiment of the invention that has been disclosed may be modified to meet various requirements.

Having described the invention, I claim:

1. Indicating mechanism 'for a condition-responsive instrument having a certain norm comprising, in combination, a condition-responsive element actuated by changes of the condition under measurement by said instrument, a condenser plate mounted on said condition-responsive element, a member positionable adjacent the path of said condenser plate for establishing such norm, a pair of condenser plates mounted on said equidistantly between the two plates 38 and 39 (as shown in Figs. III and XI), the capacities of the two condhsers formed by the common plate 40 and the' plate 38, and the common plate 40 and the plate 39, are equal, and thus both the A signal and the "N signal are transmitted through the circuit and, since they are intermeshed by the action of the cam, a continuous loud tone is audible in the earphones 4I. When the pointer moves to the right of its central position, the capacity of the condenser formed by the common plate 40 and the plate 39 increases, and the dash-dot N signal becomes increasingly audible until the indicator has moved some slight distance to the right and the condenser plate 40 is positioned over only thc condenser plate 39. At this point a loud N signal is audible on the earphones 4|. Thereafter as the indicator moves further to the right, the capacity of the condenser decreases due to the disparity in radii and the N signal decreases in volume.

Thus the signal audible, i. e., whether an N or an, A,. indicates whether the scale is above or below balance and consequently whether the load being weighed is larger or smaller than the desired load and the change in volume from a less audible signal and a moreaudible signal (or vice versa) indicates approach to or movement away from) a balance condition. The balance condition is indicated bya change from the .A signal if weight has been added, or a change from the N signal if the weight was originally too great and some of it has been removed, to a single continuous tone.

By changing the values of the various resistances and condensers, and by changing the size of the condenser plates, the sensitivity of the audible indicating means may be varied at will.

It is to be understood that the audible indimember, one on each side of the central norm 7 position, said pair of condenser plates being shaped so as to be slightly more distant from the path of said common condenser plate at their far ends than at their near ends, and electrical apparatus including a device for creating two electrical signals of different characteristics, an electrical circuit 4leading to said device and having two parallel branches therebeyond, a, diilerent one of said signals being transmitted through each oi' said branches, a different one of said pair of condenser plates being located in each of said branches, said common condenser plate being located in said main circuit` and means for rendering audible said electrical signals, whereby the position of said condition-responsive element relative to such norm is indicated by that one of said signals which is audible and approach to such norm is indicated by increased volume of said signal.

2. In a weighing scale, in combination, weighing mechanism including a load receiver and an indicator movable in response to loads applied to said load receiver, means for audibly indicating the condition of balance of said weighing mechanism, said means comprising an electrical device for creating two signals of different characteristics, two circuits from said device one for each signal each including an impedance element adjacent the path of said indicator, a common element on said indicator, and means for rendering the signals passed through said impedance elements audible, said impedance elements being characterized by presenting a high impedance to the now of signal current when the indicator is remote from a selected balance point, ysaid impedance decreasing as said balance point is approached and sharply increasing as said balance point is passed, whereby an audible signal of one characteristic apparent with an unbalance increases in amplitude as .balance is approached, merges with the signal of the other characteristic at balance, and sharply decreases in amplitude when the balance point is passed.

LAWRENCE S. WILLIAMS. 

